[CLI] nitrostack generate: implement or clearly scope stub generators

[cloud-nitrostack]

nitrostack generate — implement or clearly scope stub generators

Summary: Some generator paths are TODO stubs or placeholder descriptions.

Where to change: typescript/packages/cli/src/commands/generate.ts.

Acceptance criteria:

• Either working generators or explicit "not implemented" error with link to docs or checklist in README listing supported generate types.

Suggested labels: dx, cli, discussion

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Source: docs/STARTER_ISSUES_REVIEW.md — edit in-repo first, then sync GitHub issues if needed.